PROJECT SUMMARY/ABSTRACT Novel patient care models, such as patient-centered medical homes (PCMH), are critical for innovating and improving the delivery of primary care. To date, the majority of research has focused on delivery mechanisms, how best to implement practice transformation, and the effects on patient care quality and health outcomes. However, no research has yet evaluated the costs associated with transforming primary care practices to PCMH. The lack of reliable cost studies makes it difficult for practices to consider and plan for PCMH transformation and for policy makers to evaluate policies around PCMH. In the proposed research, we will fill this gap by collecting direct and indirect cost data on PCMH transformation from practices that have gone through the process. This will be the first research to evaluate these costs and so will be essential to informing PCMH transformation decisions and policy making. Our research team is currently conducting a large study of the effect of primary care practice transformation in eight states entitled Multi-payer Advanced Primary Care Practice (MAPCP) that is funded by the Centers for Medicare & Medicaid Services (CMS). We propose to survey the practices participating in this study to acquire supplemental data on the costs of practice transformation. Both CMS and the practices participating in the MAPCP Demonstration Project have expressed interest in understanding the costs associated with primary care practice transformation, so survey participation is expected to be strong. By building off of the MAPCP Demonstration Project, the proposed cost study will take advantage of this large and relatively diverse sample of primary care practices that have already gone through transition and will be able to use the detailed data collected in the MAPCP project. We will survey MAPCP practices about the costs of each element of practice transformation and use the data to examine the following research questions: What is the average cost of transformation for each practice transformation element? What is the distribution of costs across resource components (labor, consultants, materials/travel/services, and contracted services) for each practice transformation element? How do transformation costs vary by practice characteristics, such as size and geography? Tying the costs of transformation to the benefits measured in our other MAPCP research, what is the cost-effectiveness of PCMH transformation? These research questions will provide essential information for practices considering PCMH transformation and for policy makers weighing the costs and benefits of promoting PCMH transformation.